PT2399 Circuits?

Project_2501 · Joined: Jan 31, 2018 Posts: 68 Location: Los Angeles

Just came across the pt2399 datasheet.

Has anyone have an circuit/stripboard layout with the pt2399? If not, I'll take my time and make my own for fun.

PHOBoS · Posted: Wed Jul 31, 2019 4:07 pm Post subject: Re: PT2399 Circuits?

no stripboards but I was actually looking for a simple PT2399 circuit yesterday and came across this one: https://sound-au.com/project26a.htm

Ayab · Joined: Oct 27, 2015 Posts: 186 Location: London, UK

There is also the "Zeitgeist" pt2399 circuit about here somewhere on E-M.

Attached is the Scott Bernardi circuit, a well known one. See some notes from the forum (not mine):

The regulator circuit is separate from the main circuit so jumper from +V to non-reg in and jumper from reg 5V out to direct reg 5V in.

Pin4 on the pt2399 is digital ground and is connected internally to pin3 (analogue gnd) via approx 10 ohm. So no need to connect anything to the 'digital gnd' pad.

Resistor marked free will set the range of your delay pot (use 100k pot), use 25K trimmer so there is no dead space when you turn the pot.

N.B. Silkscreen/wiring plan shows potentiometers represented seen from the bottom view not the top view.

Works on 12V (replace 47k next to purple in front of Mix Pot connections with jumper)

Hope that is useful

Scott Bernardi pt2399_wiring layout showing R7 in purple and jumper.gif

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ScottBernardi_VCdelay schemo.pdf

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ScottBernardi_VCdelay_PCB.pdf

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Grumble · Posted: Wed Jul 31, 2019 10:01 pm Post subject:

ordered this: https://nl.aliexpress.com/item/32870335319.html

havent built it yet, but for $2.86 Rolling Eyes

print plus components...

Project_2501 · Joined: Jan 31, 2018 Posts: 68 Location: Los Angeles

After combing through ebay, seems like the guitar pedal community has many pt2399 options.

https://www.ebay.com/itm/DIY-KIT-FOR-GUITAR-DIGITAL-AUDIO-ECHO-DELAY-PT2399-MIX-FEEDBACK-DELAY/223055205453?hash=item33ef20544d:g:Et4AAOSw7P5bO3GW

roughly $15 for a full board & BOM. Not to bad.

Synthrotek offers a kit as well, but it's $30.

I'm looking forward for the delay feature. After listening to some electronic noise, I love delay vibes.

I'll order someone within the month to toy with, I'll report back when I have some sounds to share.

ceero · Joined: Jul 25, 2019 Posts: 2 Location: Norway

I haven't made this one yet, but it's on my to-do list:

https://cdn.makezine.com/make/blogs/blog.makezine.com/upload/2009/10/build_an_experimental_echo_pedal/Echobenderrev02.jpg

efluon · Joined: Jul 20, 2019 Posts: 8 Location: Hamburg

Most simple:
http://www.st-modular.com/delay.htm

Most flexible:
https://www.electrosmash.com/time-manipulator

Ayab · Joined: Oct 27, 2015 Posts: 186 Location: London, UK

Joe Beuckman has very generously posted his Eagle version of the Scott Bernardi PT2399 VC Echo on GitHub.

https://github.com/jbeuckm/pt2399_echo

You can download the Eagle software for free then load Joe's PT2399 design, convert it to Gerber files and send it to a pcb making house like OSH Park. There are also panel designs I think.

And there are many other classic module designs for eurorack on Joe's Github.

cyclic · Joined: Mar 15, 2015 Posts: 95 Location: hobart

Actually, i think that pt2399 he has is more or less the standard datasheet pt2399, although he does include the vc version elsewhere on his github which is available elsewhere, but not as eagle files, just the b&w artwork.

But thanks.for linking, he does have some good stuff for me to tinker with, and to do some dual sided etch tests without the work of laying them out fully...

cyclic · Joined: Mar 15, 2015 Posts: 95 Location: hobart

I should have also said I just bodged together a working vc pt2399 with one of the many simple circuits available (probably the same as the el cheapo complete board linked to above) and with fully homerolled diy vactrol control.

Its far from smooth or linear or logarythmic in its vc response, but it does well enough for a cheap board with 2 stripboard daughterboards for each vc input. I used the 'voltage to resistance' schems from http://thesquarewaveparade.com/images/VtoR.jpg

Basically used the most complex one but with just one attenuated input and a trimpot and wired the resitance directly across the feedback and delay pots, so the original pots act as a preset level. I also used the ljn to log pot hack for the inout attenuator as it unsurprisingly seems to give better led drive response.

Ayab · Joined: Oct 27, 2015 Posts: 186 Location: London, UK

Hi Cyclic

You are right. I actually meant to link to the PT2399 VC on Joe's github (and yes this one is not the eagle files but for diy etching):

https://github.com/jbeuckm/ScottBernardi-VCdelay-PCB

I have had bad luck with double sided etching - probably because I tried some smt! Was just not forgiving enough on the lining up.

Interesting to know about your PT2399 with diy vactrol control. Cool and the gang! Hope your builds are going well.

cslammy · Posted: Mon Jun 29, 2020 12:37 pm Post subject: Wet/Dry?

Hi there

I've built up the PT2399 based on the factory spec sheet as a start.

http://audiodiwhy.blogspot.com/2020/06/pt2399-based-synthesizer-echo-pt-cruiser.html

I am now beginning the process of modding this circuit.

I already have a simple effects send/receive where you put a VCA into the echo loop for CV control of echo (turns out: really easy mod).

Question, I want to add a wet/dry control to a PT2399 design.

I see Befaco has that on their "Crush 3" PT2399 but I can't understand how it works--seems like they use two stages of a 13700 OTA for this, but still, not sure.

How would that work?

I'd want to get rid of the source signal somehow and just end up with the rest of the echo signal (so--what goes back into pin 16, controlled by the feedback pot, only), but I can't see how you can do that w/ the PT2399

Perhaps invert the input and sum it back in to the ECHO signal to only get "everything else BUT input"? (but that would in some cases kill the feedback frequencies as well?)

Does anyone know of a PT2399 design where someone has already figured this out? Maybe something simple I am missing?

Thanks in advance.

gabbagabi · Posted: Mon Jun 29, 2020 10:26 pm Post subject:

the simplest solution that comes to MY mind is attached

ife build two of the Rebote2.5 back in the days
http://www.tonepad.com/getFile.asp?id=98
there you could see how THEY mix together the dry and the wet

nass oder trocken.png

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